Definitions
1.nounA pervasive neurological disorder that is observable in early childhood and persists throughout the lifespan, characterised by atypical communication, language development, eye contact, and sensory experiences.
2.noun(now medically obsolete) A diagnosis involving a pathological tendency to engage in self-centered fantasy thinking, historically considered a symptom of insanity and/or schizophrenia.
3.noun(4chan) Abnormal and unhealthy focus or persistence, and unhealthy hatred of opposition or criticism.
4.nounThe range of conditions classified as pervasive developmental disorders, generally held to include autistic disorder, Asperger syndrome, and pervasive developmental disorder - not otherwise specified (PDD-NOS). Also includes childhood disintegrative disorder and Rett syndrome.